Patent GB-610528-A (GB)
Title: Improvements relating to electric remote control systems
IPC: G05D3/12
Filed: 1945-08-30
Abstract: 610,528. Photo-electric systems for remote selective control. JENNINGS, H. W. K. (Homrighous, J. H.). Aug. 30, 1945, No. 22386. [Class 40 (i)] [Also in Groups XL (b) and XL (c)] A system of remote control has a television receiver co-operating with cells viewing in. dividual areas of the screen, the cells controlling motors, and a transmitter with a movable image member for changing the transmitted signal in accordance with the manner in which the motors are to be controlled. Each receiver has cells, e.g. 141, 142, &c., Fig. 17, viewing different points, e.g. 137 of the screen, and the cells control series connected relays which actuate an exploder, Fig. 18 (not shown). The screen area may be in the form of a clock face, Fig. 20 (not shown), or may be divided into areas, Fig. 21 (not shown). Some of the relays may be actuated when the co-operating screen areas are black to prevent actuation by an allwhite picture. For steering a vehicle, the transmitter comprises a white spot 167, Fig. 24, rotatable on a white ground by a handle 166. The receiver on the vehicle co-operates with cells O, R<SP>1</SP>, R<SP>2</SP>, &c., and L<SP>1</SP> &c., Fig. 23 viewing adjacent areas on the screen. The cells selectively operate relays, Fig. 22 (not shown), controlling two motors, so that when cell O views a white spot, both motors run at equal speed, but when cells R<SP>1</SP> or L<SP>1</SP> are affected by the white spot, the appropriate relays are actuated to cut out a resistance from the circuit of one of the motors to cause turning. Cells R2 &c. cause the removal of further resistance to reduce the radius of turning. In a modification, cells 183, 185, Fig. 25, are held in a constant direction with regard to space by a compass, and view diametrally opposed areas of a cathode-ray screen carried on the vehicle. When both cells are unilluminated, motors driving the vehicle run at equal speed. The screen at the transmitter, Fig. 26, is rotatable as desired, so that its image at the receiver can rotate to illuminate one of the cells. The illuminated cell operates a relay to cause variation of speed of one of the motors, and turn the vehicle so that the cathode-ray screen carried by the vehicle rotates under the compass-controlled cells until both cells are again unilluminated. Calling.-The receiver may be rendered operative by a calling signal of a particular frequency. A circuit 96, 97, Fig. 10, tuned to the carrier feeds a rectifier 98 (e.g. a crystal electron) to supply the calling signal to a tuned relay 99 which operates a slow release relay 102 to complete the supply circuits of the receiver proper and to complete a heating circuit for a bimetallic strip 94 to switch in the aerial circuit 106. Relay 102 is maintained by current from a cell 112 viewing a bright code mark on the receiver screen, so that by suitable choice of position of the bright spot and co-operating cell selective energization of receivers can be obtained. Alternatively, cell 112 may actuate a relay 115, whose contacts will complete supply circuits. Synchronizing signals.- The transmitter is preferably of the cathode-ray tube type and synchronizing signals may be developed by scanning an appropriately shaded area or by modulating oscillations of field frequency on an adjacent carrier, Fig. 1 (not shown). A motor 32, Fig. 3, rotates a drum 33 once per frame, and block zones 34, 35 are imaged on the transmitting tube. Simultaneously, cells 41, 42 receive light through polarisers 37, 38 and a rotating disc 36 of which one half 36, Fig. 4, is opaque and the other half of polarising material, so that each cell is operative in turn, and their outputs are combined, Fig. 5 (not shown), to produce a sinusoidal oscillation of field frequency (one half frame frequency) This oscillation may be transmitted on a separate carrier. Line frequency synchronizing signals may be developed by frequency multiplication, e.g. by a plurality of full wave rectification stages, Fig. 6 (not shown). Thus, the number of frames/sec. can be varied by varying the speed of the motor 32, and the number of lines/frame can be varied by switching in or out stages of frequency doubling; where the number of lines/frame is varied, the size of the scanning spot is also varied. The sinusoidal oscillations control the discharge of a condenser producing saw-tooth oscillations for scanning, Fig. 7 (not shown). When the synchronizing signals are producing by scanning an appropriately shaded area, a cell at the receiver view the corresponding area and its output is used to discharge the condenser producing saw-tooth scanning oscillations, Figs. 2, 13 (not shown); to start scanning at the receiver in such circumstances, the cathode-ray beam normally rests at one corner of the screen, and an initial transmission of a suitably shaded screen, Fig. 15 (not shown), is used to modulate the spot at the receiver and affect the viewing cell to discharge the condenser producing sawtooth oscillations. Interlacing is produced by varying the potential on the field deflecting the plates at the receiver from field to field. The sinusoidal synchronizing signals are rectified to produce signals 76, Fig. 9, to control a relay 84 or valve 78 to alter the potential of line 80 from to provide the displacement of the field. Field controlling impulses 73 are produced by fullwave rectification of the received sinusoidal oscillations. Secrecy may be ensured by transmission on different carriers, by variation of number of fields or lines and by choice of interlaced or progressive scanning as well as by choice of transmitted pattern.